lwp: Fix handling of sigismember() failure

[empserver] / src / lib / lwp / sig.c

diff --git a/src/lib/lwp/sig.c b/src/lib/lwp/sig.c
index 104478e6633f220011dd04482fb7c0ab64437c90..04fb9f97741dba4d645c893673d3a8aa4e029afe 100644 (file)
--- a/src/lib/lwp/sig.c
+++ b/src/lib/lwp/sig.c
@@ -1,11 +1,11 @@
 /*
  *  Empire - A multi-player, client/server Internet based war game.
- *  Copyright (C) 1994-2006, Dave Pare, Jeff Bailey, Thomas Ruschak,
- *                           Ken Stevens, Steve McClure
+ *  Copyright (C) 1994-2020, Dave Pare, Jeff Bailey, Thomas Ruschak,
+ *                Ken Stevens, Steve McClure, Markus Armbruster
  *
- *  This program is free software; you can redistribute it and/or modify
+ *  Empire is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
- *  the Free Software Foundation; either version 2 of the License, or
+ *  the Free Software Foundation, either version 3 of the License, or
  *  (at your option) any later version.
  *
  *  This program is distributed in the hope that it will be useful,
@@ -14,8 +14,7 @@
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
- *  along with this program; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  *
  *  ---
  *
@@ -26,37 +25,37 @@
  *  ---
  *
  *  sig.c: Wait for signals
- * 
+ *
  *  Known contributors to this file:
- *     Markus Armbruster, 2006
+ *     Markus Armbruster, 2006-2020
  */
 
 #include <config.h>
 
 #include <errno.h>
+#include <stddef.h>
 #include <signal.h>
 #include "lwp.h"
 #include "lwpint.h"
 
-/* Signals awaited by lwpSigWait() */
-static sigset_t *LwpSigAwaited;
-
 /*
- * Signals from LwpSigAwaited catched so far
+ * Signals caught so far.
  * Access only with signals blocked!
  */
-static sigset_t LwpSigCatched;
+static sigset_t LwpSigCaught;
+
+/*
+ * LwpSigCaught changed since last
+ */
+static sig_atomic_t LwpSigCheck;
 
 /* The thread waiting for signals in lwpSigWait() */
 static struct lwpProc *LwpSigWaiter;
 
-/* Where to return the signal number to the thread in lwpSigWait() */
-static int *LwpSigPtr;
-
 static void lwpCatchAwaitedSig(int);
 
 /*
- * Initialize waiting for signals in SET.
+ * Initialize waiting for signals in @set.
  */
 void
 lwpInitSigWait(sigset_t *set)
@@ -64,14 +63,13 @@ lwpInitSigWait(sigset_t *set)
     struct sigaction act;
     int i;
 
-    sigemptyset(&LwpSigCatched);
+    sigemptyset(&LwpSigCaught);
 
     act.sa_flags = 0;
     act.sa_mask = *set;
-    sigemptyset(&act.sa_mask);
     act.sa_handler = lwpCatchAwaitedSig;
     for (i = 0; i < NSIG; i++) {
-       if (sigismember(set, i))
+       if (sigismember(set, i) > 0)
            sigaction(i, &act, NULL);
     }
 }
@@ -79,12 +77,13 @@ lwpInitSigWait(sigset_t *set)
 static void
 lwpCatchAwaitedSig(int sig)
 {
-    sigaddset(&LwpSigCatched, sig);
+    sigaddset(&LwpSigCaught, sig);
+    LwpSigCheck = 1;
 }
 
 /*
- * Test whether a signal from SET has been catched.
- * If yes, delete that signal from the set of catched signals, and
+ * Test whether a signal from @set has been caught.
+ * If yes, delete that signal from the set of caught signals, and
  * return its number.
  * Else return 0.
  */
@@ -96,9 +95,9 @@ lwpGetSig(sigset_t *set)
 
     sigprocmask(SIG_BLOCK, set, &save);
     for (i = NSIG - 1; i > 0; i--) {
-       if (sigismember(set, i) && sigismember(&LwpSigCatched, i)) {
+       if (sigismember(set, i) > 0 && sigismember(&LwpSigCaught, i) > 0) {
            lwpStatus(LwpCurrent, "Got awaited signal %d", i);
-           sigdelset(&LwpSigCatched, i);
+           sigdelset(&LwpSigCaught, i);
            break;
        }
     }
@@ -107,8 +106,8 @@ lwpGetSig(sigset_t *set)
 }
 
 /*
- * Wait until a signal from SET arrives.
- * Assign its number to *SIG and return 0.
+ * Wait until a signal from @set arrives.
+ * Assign its number to *@sig and return 0.
  * If another thread is already waiting for signals, return EBUSY
  * without waiting.
  */
@@ -117,16 +116,16 @@ lwpSigWait(sigset_t *set, int *sig)
 {
     int res;
 
-    if (CANT_HAPPEN(LwpSigWaiter))
+    if (LwpSigWaiter)
        return EBUSY;
-    res = lwpGetSig(set);
-    if (res <= 0) {
+    for (;;) {
+       LwpSigCheck = 0;
+       res = lwpGetSig(set);
+       if (res > 0)
+           break;
        lwpStatus(LwpCurrent, "Waiting for signals");
-       LwpSigAwaited = set;
-       LwpSigPtr = sig;
        LwpSigWaiter = LwpCurrent;
        lwpReschedule();
-       return 0;
     }
     *sig = res;
     return 0;
@@ -139,13 +138,7 @@ lwpSigWait(sigset_t *set, int *sig)
 void
 lwpSigWakeup(void)
 {
-    int res;
-
-    if (!LwpSigWaiter)
-       return;
-    res = lwpGetSig(LwpSigAwaited);
-    if (res > 0) {
-       *LwpSigPtr = res;
+    if (LwpSigWaiter && LwpSigCheck) {
        lwpReady(LwpSigWaiter);
        LwpSigWaiter = NULL;
     }